The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory captions and links exemplifying features within the Earth system. The community is invited to contribute digital imagery, short captions and relevant links.

Shadow Bands of the Great American Eclipse

Many of you who viewed last month's Great American Eclipse could clearly see the beautiful solar corona that hugs the Sun during a total solar eclipse, but there are other wonders that can also be seen during such eclipses, including shadow bands. Though observed by humans for thousands of years, the mysterious shadow bands associated with total solar eclipses are sill poorly understood. If you have a low horizon, you may be able to spot them a few minutes before totality as they start appearing far away from you. They then race over the landscape (at over 1,500 mph or 2,415 km/hr), seemingly getting closer and closer to an observer and intensifying as totality approaches. A few seconds before the totality, you might spot them just below your feet. The same sequence repeats after the totality. The intensity of these bands may be different before and after totality. It's believed that they're caused by fluctuations in the light rays (sunlight) passing through the turbulentEarth's atmosphere. Turbulent air cells are thought to behave like lenses, focusing and de-focusing sunlight just before and just totality occurs. The bands, sometimes seen in the form of ripples, are constantly in motion and changing as they move, enveloping everything in their path.

Shadow bands are very difficult to capture on still photography or during filming. Most people try to utilize some sort of white material to film the slightly darker shadow as it races by. However, I decided it would be much more interesting to capture the shadows in the wild, applying a wide-angle, time-lapse approach. The video you're about to see is composed of four parts. The first is the original eclipse video where you'll be able to see jet contrails (from NASA aircraft), the Moon's shadow moving in front of the solar disk and then during totality, as the day suddenly turns into the night, sunset colors rimming the horizon. The next three parts are enhanced crops of the original video. Note that the shadow bands first appear on the field in the far distance. As totality nears, the keen-eyed viewer may see the bands come closer and closer and even intensify. Just before totality, they reached the dirt road where I was filming, near Fruitland, Idaho.

Below is a time-lapse made during the eclipse of August 21, 2017, and see if you can detect these elusive bands. Don't worry if you can't spot them during the first part. They're easier to see on the cropped and enhanced versions. Nonetheless, the bands are still hard to detect. For best results, watch this video on your PC's monitor and not on a smart phone.